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Building a Homemade Fuel-Injection System on a Briggs and Stratton 5 HP Engine

Building a Homemade Fuel-Injection System on a Briggs and Stratton 5 HP Engine

I had a 1976 SAAB that had a mechanical fuel injection system. I was very
simple and that motor had LOTS of balls. In 1976 most cars were nothing but
smog pumps, but that old Saab didn't need any of the emissions stuff and ran
very good.

Building a Homemade Fuel-Injection System on a Briggs and Stratton 5 HP Engine

Think the "Karters" are already doing this. Especially the alcohol burners.
Quite easy. They divert the pressure diaphram lift pump that fills the
resevoir in the tank "float level" to the main mixture screw. From there
straight into the carburetor using the existing port. They use the mixture
screw to set the maximum mixture setting and let the rest go. Vacuum does
not pull the fuel in. The system is pressurized. Works quite well for a
racing setup.

Building a Homemade Fuel-Injection System on a Briggs and Stratton 5 HP Engine

Ecnerwal wrote:
Let's see - you need an O2 sensor, you need a fuel pump, you need an
injector, and you need a little computer to control it all. You may also
need an array of other sensors, such as various temperature readings. So
you'll be adding a generator if the mower does not have one. If it were
me I'd add a better muffler along with the O2 sensor, since I just don't
think the standard lawnmower exhaust is even remotely quiet enough.

Gross overkill for the application. SInce you wish to operate at
essentially constant rpm and nearly constant power at fairly well known
temperature and pressure, the requirements are much less. Cars need to
run over a wide range of environmetal conditions and over a wide range
of speed and torque.

In the late 60's, I had a Cessna 205 which had an injected engine.
There was a fuel pump and a bypass valve to control the pressure at the
injectors and a throttle butterfly to control the air. IIRC, the
throttle affected both the bypass and the butterfly and the mixture
control affected the fuel pump or possibly was tied into the bypass.
The injectors were partially pinched of pieces of copper tube that
sprayed the fuel into the manifold just before the intake valves.
Performance was good as was fuel consumption so the simple system
obviously worked.

I was rather amazed
at the expertise of a 21-yr old mechanical engineer to pull this off!
(The graduate-level electrical engineer working on the electronics for
the main DC motor drive was ALL wet, ignored all my advice, and
ended up with a car powered by a 90 Hp electric motor plowing sideways
through a room full of people when the main power transistor shorted.
There were people climbing benches and whatever to get out of the way!
Luckily, no injuries on that one.)

And now she's a mom with three kids, and he designs Mars landers,
right? G
************************************************** ***
It's not the milk and honey we hate. It's having it
rammed down our throats.

I was rather amazed
at the expertise of a 21-yr old mechanical engineer to pull this off!

(Snip)
And now she's a mom with three kids, and he designs Mars landers,
right? G
************************************************** ***
It's not the milk and honey we hate. It's having it
rammed down our throats.

Building a Homemade Fuel-Injection System on a Briggs and Stratton 5 HP Engine

"Todd Rearick" wrote in message news:[email protected]..
You know...I've wondered the same thing. I have an old Toro lawn mower that
I use for odd jobs around the house. I think it was made in '75 or there
abouts. Anway, It's a bit finicky to get started...easy to flood and really
touchy to adjust the choke right. I'm sure most would call me crazy, but I
think it would be a fun project to build a FI system for it.

Sorry...I don't really have any info or links...just moral support.

"T.C. Mann" wrote in message
m...
Hello,

I would like to know if anyone has ever tried to implement a FI system
for use on a small lawn mower engine. What would be involved in doing
this and would it work? Are there any DIY sites that discuss this or
are plans available? Any other good references? Thanks a bunch.

I have contemplated this for a long time, but have never gotten around
to actually DOING it. I have always wanted to build my own fuel
injection system. I was thinking of injecting my VW dune buggy.
Maybe get real crazy and turbo it someday(but I doubt it).
I was on the SAE formula team in college. We modified a Haltech(I
think?) injection system to run a bike motor. It worked fairly well.
The engine controls has always been a cool idea to me. I want to do
it, just to do it. If I had a serious application I would buy one of
the generic off-the-shelf packages available out there, like what have
been suggested. A co-worker has the megasquirt system on his Audi
turbo. Currently, just using it for spark control I believe, and
waiting to tie in the fuel.

Building a Homemade Fuel-Injection System on a Briggs and Stratton 5 HP Engine

You know...I've wondered the same thing. I have an old Toro lawn mower
that

biggest prob. will be to manage that little amount of fuel. i have built a
couple for harleys and the idle circuit is the one that requires the attention
to flow. but it is pretty easy one you get the basic principle down pat. volume
and pressure are the only things you need to control.
"try it-you'll like it"
jim

Building a Homemade Fuel-Injection System on a Briggs and Stratton 5 HP Engine

"T.C. Mann" wrote in message
m...
Hello,

I would like to know if anyone has ever tried to implement a FI system
for use on a small lawn mower engine. What would be involved in doing
this and would it work? Are there any DIY sites that discuss this or
are plans available? Any other good references? Thanks a bunch.

IIRC the January 2002 issue of Circuit Cellar magazine had an article about
home-brew fuel injection.